In the existing art, conventional point or spot light sources (usually halogen lamps) are used for incident illumination in microscopes having a long working distance, such as zoom microscopes; usually the object is illuminated not through the objective but separately therefrom. Light is guided directly or via a fiber bundle to the sample stage. Such illumination devices, as disclosed for example in DE 101 23 785 A1 or DE 101 33 064 A1, usually do not generate homogeneous illumination, which can result in weak contrast and possibly in illumination artifacts such as reflections, shadows, and so forth. They also require a great deal of space in the vicinity of the microscope. In addition, coupling the light source into a fiber bundle and subsequently recoupling it into a diffusing attachment results in appreciable efficiency losses.
It is desirable to describe an incident illumination device for a microscope which is as flat as possible but nevertheless homogeneous.